Author
Topic: How I have made these things (Read 28734 times)

I will go into more detail on this subject later but want to get a post in here to get it started.

On my first geared device, I ground an old HSS router bit to approximate shape and cut teeth with a router mounted in my metal lathe and a home made index. They worked OK but didn't look the way I wanted. The index was not very good so I then bought a dividing head from Grizzy for, I think, less than $300 and mounted it on my lathe so that I could get good accurate indexing. That improved the effort but it was still far from perfect.

Some time passed and I obtained a copy of a book, "Gears fpr Small Mechanisms" by Davis and, having also learned to use a CAD program figured out how to draw good cycloidal teeth. This took me some considerable amount of time because it requires thought and concentration, hard commodities to acquire when one is out of practice. I then bought a CAM package to go with the CAD, (Bob CadCam) and was able to produce G code for my machining center and make perfect wheels and pinions. Now this was a long, expensive proceedure and there are numerous other ways to get good results but I am convinced that if you are wealthy enough and crazy enough, this is the best of all possible ways to produce gearing.

The standard, time honored method of gear cutting requires precision ground cutters, and a good lathe with indexing. This will produce excellent gears but the problem is that there are no cutters available that are large enough for wooden wheels and pinions. They are available for brass clocks but wood requires teeth which are at least slightly larger than the largest brass gear cutters made. An enterprising philanthropist could probably have a series of proper cutters made at considerable espense, which he could then sell at reasonable cost to the rest of us. So if there is such an exemplary individual out there, this is your chance to serve humanity.

JoeComunale

I had the pleasure of a visit to JR's shop - it's a lot like getting sent to Santa's workshop - lots of really neat inventions and gizmo's for a mechanically intuitive mind to feast on.

JR demonstrated how he had cut his gears (Wheels and Pinions) on his CNC machining center (a Haas used for his business). I had just completed piecing together a small home CNC milling machine (Sherline with Servo drives) - and this was just the ticket to exercise my mind and mill.

Armed with the Grasshopper article (also from JR), inspiration and information from JR - I dove in. I have completed making my gears, and am now in the process or re-making my grasshopper mechanism. I hope to have my clock running in the near future (time and work permitting).

I will say - it the CNC milling machine really makes gear variation a possibility. If you had an indexing set-up and cycloidal tooth flycutters - you could do a very good job at making these gears. The only problem is - if you ever want a different module (pitch) - you need a new flycutter. That's where the flexibility of the CNC milling machin excels.

(Just my $.02 worth)

Logged

JayRay_Hughes

I haven’t a shop, nor the money to get some of these tools, So I put my brain to work. What I came up with is to CAD up templates and have them cut with a laser cutter. Then rout them out. I am hopefully going to the laser cutters for the first time next week. With any luck I will let you know how it went within 3 weeks.

JayRay_Hughes

I was going to cut them out of a plastic material. I know about the roughness. i am hoping that when used as a templat with 1/8 inch guided bit that it will take out most of that. If not than i may haft to sand. Still in the experiment stage. It may not work either.

Logged

Anonymous

OK, I will try to explain the idea. I have seen these table saw blades that hold a piece of steel or solid carbide on the end. They are changeable and you can make molding with your table saw. Cut a dozen gears at once.

Next. I watched somebody custom grind a blade for a profile hand plane with a dremil and a jig. Very accurate and fast with the right set up. He basicly buffed the final shape to sharpness.

The Idea. Buy this special blade for the saw and make your own cutters and use a jig to index and position the gear. Cut teeth one at a time on your table saw.

Also I think you can get custom cutters for like $100. Carbide for like $250

Yes that would probably work. I have a single cutter head like that and I have ground custom blades for molding in just that way. You would have to make a sled to hold a mandrel with a stack of wheels on it and have a good accurate index arrangement. It would be a failry dangerous setup though and I think there may be easier ways. We all have to work with the tools we have, though, so sometimes the best way is just not available.

Logged

JayRay_Hughes

If I do this, I will have help from my instructor at school. Beleive me, Safty will be the highest priority. In fact some things that were ok to do in a production cabinet shop are not here. Thats ok with me. I am learning the best way to keep my figures.

Logged

JoeComunale

I have seen this type of set-up before - in a Fine Woodworking book. But the regular table saw blade was used to produce Escape style gears (i.e. non-cycloidal and non-involute tooth profile). The figure showed only making one gear at a time - but making multiple copies on a mandrel with an indexing plate is entirely possible (as JR described).

I guess it depends on how many of the same clock gear you need to produce (I don't expect a similar market as that of the late 1700's when Great Britain embargoed the US from brass, steel, etc - causing the boom years of woodworks clocks). :)

Logged

Damon Miller

It is difficult for me to understand why one would want to mass produce a wheel or pinion for a wooden gear clock. As has been pointed out each change in center distance alters the tooth profile, thus one wheel/pinion does not fit all. My understanding of the wooden gear clock history leads me to believe that these timepieces were made one at a time mostly for the makers use. I also find great pleasure in the working of the woods and making one wheel/pinion at a time for a given configuration. That is my 1/2 cents worth.

Logged

JoeComunale

At one time - wood works (all or nearly all gears (Wheels, Pinions), arbors, etc.) - were mass produced. During the years following winning our independance from Great Britain - who embargoed us from steel, brass, etc. - a boon market for wood works clocks existed. Literally 10's of thousands of clocks were made with with "wood works".

This also meant that the average man could afford a timepiece for their house (as it was not as expensive as a hand crafted brass/steel clock) - as the clocks were mass produced - with many interchangeable parts from maker to maker. Many of these timepieces still exist today - and are still in working order keeping time.

Today - I think the ability to make multiples has a lot of use, as it can enable a craftsman to make a few copies of his work for sale. I can definitely see where my small CNC milling machine will be a great help in producing gears and what not for clocks or kinetic sculpture or "gizmo's".

I don't know that I understand your comment on changing center distance alter's tooth profile. Tooth profile - whether it is involute or cycloidal - is determined by basic gear geometry (Predominantly Pitch/Module and number of teeth in Wheel/number of teeth in pinion). The tooth profile is derived from the manner of tooth form used (e.g. "Cycloidal" or "involute"). This, then, will determine the actual tooth geometry construction. From this geometry - the pitch circle is computed, and the theoretical center-to-center distance of the Wheel/Pinion or Gear/Gear train.

Logged

Marc

Years ago I read the Westphale article in the Woodworking Magazine and knew that making woodworks was for me. The only problem was all the machinery that Westphale used was a little to costly. After much thought and research I settle on a scrollsaw. Drawing up the patterns on a CAD and sawing them out with a scrollsaw under a magnifying glass is a highly accurate process. I've also made wheels using a router. Just does not provide the satisfaction of sawing them out. The early clocksters in New England used hand tools and primitive lathes. This was their winter job since farming had to wait till springtime. Examining those early woodworks revealed that the teeth were sawn by hand and none alike! Around 1810 Eli Terry had a contract with the Porters to manufacture 4,000 woodworks. Enters the sawmill that was water powered. I owned number 3706 and what an improvement over the hand made ones. Now we have all the latest equipment and can make a much improved timepiece. However, there is much more to making woodworks than designing perfect teeth and pinions. Those early clocks ran on or about three pounds of weight for thiry hours. Eight day clocks ran on or about 7.5 pounds. Those early clocksters were amazing. My favorite is Jesse Emory. His clocks were beautifully engineered. The time train that I made using his design ran on 15 ounces. He used a three pound weight to overcome those little problems of dust, dirt, and bugs getting in between the wheels and pinions.Glad to see this forum up and running. Nothing like exchanging ideas on this great hobby.Marc TovarLayton, UT